When it comes to dry powder inhalation (DPI), adhesive mixtures are the most widely used formulation type. Various techniques have been developed to generate inhaled drug particles and improve the delivery efficiency of DPI formulations. For dry powder inhaler formulations (DPIs), micronized drug powders are usually mixed with lactose carriers to improve powder handling during manufacturing and powder aerosol delivery during patient use. The performance of DPI systems is strongly dependent on several formulation factors, the construction of the delivery device and the inhalation technique. There is a growing interest in DPI in new medical areas such as vaccines and antibiotics which requires further development and challenges to ensure physical and aerosolization stability of DPI.  This project aims to discuss the development of inhalation therapy, the challenges during formulation processes, the mixing process and the use of excipients in pulmonary drug delivery in DPIs. Further, the project is covered by experiments based on the literature overview and performed at the Department of Pharmaceutical Biosciences at Uppsala University. Bulk density was measured on three series of adhesive mixtures with increasing amounts of fine particles. In two series, small amounts of Magnesium Stearate, 0,1% and 0,01% were added.